cavsdec: check for value in get_ue_code()

Fixes integer overflow and prints an error in case the value is
invalid.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
h264_qpel: put cpuflags checks back.

These where lost when libav moved the code out of dsputil

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>